Philippe Mourere is CEO of Vector Laboratories, having previously led NanoMosaic and Stilla Technologies through periods of growth, strategic development, and product expansion.
Credit: Philippe Mourere.
Bioconjugation has evolved from a laboratory technique for attaching fluorescent labels to proteins into a central technology for modern drug development. By chemically linking biomolecules to other functional components, researchers can alter properties such as stability, pharmacokinetics, tissue distribution and targeting, underpinning therapeutic approaches ranging from antibody-drug conjugates (ADCs) and radioconjugates to oligonucleotide delivery systems and molecular imaging.
The field has also become increasingly sophisticated. Advances in site-selective and bioorthogonal chemistry have given researchers greater control over where and how molecules are joined, addressing some of the limitations of earlier conjugation approaches. As drug developers look for ways to improve established therapeutic modalities, these chemical tools are taking on greater importance.
DDN spoke with Philippe Mourere, CEO of Vector Laboratories, about how advances in bioconjugation and linker chemistry are changing therapeutic design, why chemistry is regaining strategic importance in drug development, and where the field could go next.
Why do you think the biopharma industry is now pivoting towards bioconjugates?
The industry is moving beyond viewing biology and chemistry as separate disciplines and instead recognizing that the greatest opportunities lie at their intersection. What changed is that the clinical and commercial case for bioconjugates became undeniable, while new-target discovery became slower and more expensive.
Drug developers have already established powerful therapeutic modalities, and bioconjugation lets them reuse those de-risked entities and improve targeting, therapeutic index, and safety through design rather than discovery. Several of the largest recent deals in this space have been for conjugation and linker platforms rather than for antibodies or targets. The market is now recognizing chemistry as the differentiator.
Why do you think chemistry is regaining strategic importance after years of biology-led innovation?
Biology determines what to target while chemistry enables therapeutic molecules to reach their full potential in patients. The properties that most often end a program in the clinic are half-life, biodistribution, off-target toxicity, aggregation, or stability, and all of those are chemistry problems, not biology problems.
Biology has given us remarkable tools, from monoclonal antibodies to cell and gene therapies, that transformed the drug development space in the early 21st century. Now that those modalities exist, the binding constraint has shifted to governing their behavior in vivo, which is the domain of chemistry. Rather than a resurgence, this reflects a recognition that biology and chemistry govern distinct variables in molecular design, and that the chemistry-governed variables are now gating progress.
Are chemical linkers becoming the most critical design element in advanced therapeutics?
The linker is generally underestimated — its significance extends across a broad range of modalities where it governs the same fundamental variables in drug performance: the ratio of cargo to targeting moiety, the stability of that attachment in circulation, and the conditions of payload release.
In a cytotoxic conjugate, it sets the drug-to-antibody ratio and the extent of bystander activity; in a radioconjugate, it controls isotope retention and off-target dosimetry. In an antibody-oligonucleotide conjugate, it must survive serum yet permit endosomal escape of an intact nucleic acid. These parameters define the therapeutic window as an identical targeting moiety, and cargo may constitute either a medicine or a source of toxicity depending on the linker that joins them. This is why the field's most valuable assets are increasingly the conjugation and linker technologies leveraged in therapeutic design rather than the biological components.
Despite progress, challenges like instability, limited reactive sites, and linker length remain. Where do you think the biggest unsolved problems in linker chemistry still lie?
The central unsolved problem is conditional control — designing a linker that remains entirely stable in circulation and releases its payload only at the target site in response to a predictable trigger. The field continues to trade stability against release, as greater stability tends to compromise reliable release, while easier release invites leakage in circulation.
Other important challenges include achieving site-specificity without re-engineering the therapeutic in each instance, or conjugating more fragile partners such as nucleic acids, larger payloads, and delivery vehicles with selective enough chemistries to attach them without compromising the function intended for delivery.
Many bioconjugation chemistries were originally developed as research tools. What has changed to make them viable as therapeutic platforms?
A reaction adequate for labeling a therapeutic agent at the bench must clear a far higher bar to reach patients, requiring defined product homogeneity, batch-to-batch reproducibility, controlled cargo-to-payload ratios, and regulatory-grade characterization. The key development enabling this shift has been the use of precise, targeted chemical modifications that allow these products to be manufactured at scale and advanced toward regulatory submission. By applying well-controlled conjugation chemistries, it is now possible to improve therapeutic effects while building on established biological platforms rather than starting from scratch. That convergence of research and therapeutic expertise accelerates innovation across the field.
Most people think of ADCs when bioconjugates are mentioned. What other areas are they becoming critical in?
Bioconjugates offer therapeutic potential in numerous configurations beyond just ADCs. For example, antibodies can also be linked with oligonucleotides to create targeted gene therapies or attached to radioactive isotopes to enable targeted radiotherapy. Outside of therapeutic applications, bioconjugates play a huge role in diagnostics, immunoassays, and molecular imaging. By linking antibodies, antigens, or nucleic acids with reporter molecules, we create tools that enable specific detection of a target. The therapeutic and diagnostic sides of the field share the same chemistry, and that common foundation is one reason the therapeutic work has progressed so rapidly.
How important are manufacturability and reproducibility in driving this shift toward bioconjugates, compared with more complex delivery systems like nanoparticles?
Manufacturability and reproducibility are major drivers behind the growing interest in bioconjugates, particularly as developers consider how to translate promising therapies into scalable commercial products. Unlike more complex delivery systems like nanoparticles, today’s bioconjugates are typically composed of well-characterized components joined through defined conjugation chemistries, making them easier to manufacture consistently and validate from a regulatory perspective. Advances such as site-specific conjugation have further improved product homogeneity and batch-to-batch reproducibility, even at scale. While nanoparticles are still essential for applications like mRNA and gene editing, they introduce additional complexity around formulation, particle size, payload distribution, and stability that can complicate scale-up.
AI is increasingly used to optimize conjugation strategies. Where does it genuinely add value today, and where is chemistry still the limiting factor?
AI is becoming valuable for identifying promising conjugation strategies, predicting molecular behavior, and accelerating design decisions, but it can only optimize within the boundaries of existing chemistry. A model cannot conceive a new fundamentally more selective linker — it can only recombine and rank what chemists have already established. The fundamental challenge is still developing new reactions and linker chemistries with greater selectivity, stability, and functionality. AI can help us find better solutions faster, but chemistry and our experts still determine what is possible in the first place.
Looking ahead, do you expect the biggest breakthroughs to come from new targets — or from better chemical control over how existing drugs behave in the body?
I’m very convinced that we’ll see major breakthroughs through modification of existing drugs rather than through new drug discovery. We’ve already identified many promising targets, but drugs against them can be limited by properties that affect efficacy or safety, including off-target effects. Large molecules can be amended with chemical groups that improve their biological function and make them less toxic or more efficacious. Improved linker chemistry is just one example of this. Rather than thinking about biology and chemistry separately, uniting the two and becoming more creative with all the “building blocks” at our disposal has the potential to revolutionize drug development. In my view, the gains of the coming decade will derive less from identifying new targets than from precise control over how existing molecules move, release, and act within the body.
